Electric circuit breaker



C. THUMIM ELECTRIC CIRCUIT BREAKER Feb. 9, 1943.

Filed D80. 10, 1941 Inventor: Carl Thumim,

b Hi5 Attorney.

Patented Feb. 9, 1943 ELECTRIC CIRCUIT BREAKER Carl Thumim, Yeadon, Pa.,assignor to General Electric Company, a corporation of New YorkApplication December 10, 1941, Serial No. 422,387

(Cl. Nt -82) 6 Claims.

My invention relates to electric circuit breakers and more particularlyto circuit breakers which depend for their operation at least in partupon a source of fluid under pressure.

Where the operation of the circuit breaker depends to some extent atleast upon a source of fluid under pressure, there is always thepossibility of a reduction or complete failure of the pressure of thissource of fluid and, if the circuit breaker under these conditions waspermitted to operate to close or open the circuit, great damage both tothe circuit breaker and associated apparatus might result.

Accordingly, it is an object of my invention to provide an electriccircuit breaker depending at least in part upon a source of fluid underpressure for proper operation thereof in which the breaker ismechanically locked in the open or closed position in the event that thepressure falls below a predetermined value.

It is a further object of my invention to provide a new and improvedelectric circuit breaker which depends at least in part upon a source offluid under pressure for proper operation thereof.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to theaccompanying drawing in which Fig. l is a schematic diagram partly insection of an electric circuit breaker embodying my invention, and Fig.2 is an enlarged perspective view partly in section of a portion of theapparatus shown in Fig. 1.

For explanatory purposes, I have illustrated my invention as applied toa circuit breaker of the cross fluid-blast type, such as is disclosedand claimed in United States Letters Patent 2,284,842, granted June 2,1942, and assigned to the same assignee as the present application. Itwill, of course, be understood by those skilled in the art that myinvention is equally applicable to other types of circuit breakers whichdepend for their operation to a certain extent atleast upon a source offluid under pressure.

Referring now to Fig. 1 of the drawing, I have illustrated my inventionas employing a fluidblast circuit breaker ID of the cross-blast typecomprising a stationary contact II and a movable contact I2 arranged tobe operated so as to draw an arc in an arc chute I3. The fixed contact II is connected to the line terminal I4 while the movable contact I2 isconnected to the line terminal I5. Fixed contact II is provided withspring-pressed contact fingers Ila and longer arcing contact fingers II, while movable contact I2 is provided with arcing tip I2 so that, whenthe contacts separate, an arc therebetween occurs between arcing tips Ii and I2. Immediately after separation of the contacts, one terminal ofthe arc is transferred by a blast of fluid, preferably air, issuing outof conduit I5, from contact fingers I I to the contact I I" which isprovided with a tip of arc-resistant metal. The air blast from conduitI6 upon opening of the breaker drives the arc into the arc chute I3against the edges of a plurality of partitions I! in the arc chute,which partitions are transverse to the air gap and the ends of whichextend close to the path of movement of the arcing tip I2- of themovable contact I2. The circuit breaker I ii, illustrated by way ofexample in order to describe my circuit-interrupting system, is not myinvention but is described and claimed in United States Letters Patent2,284,842 referred to above.

In order to operate circuit breaker It automatically by fluid pressure,there is provided motive means comprising a cylinder is with a piston I9connected through a rod 23 to operate a lever 2! secured to the shaft22. The shaft 22 has attached thereto an arm 23 of insulating materialfor operating the movable contact I2' of the circuit breaker. Althoughcircuit breaker II] is described with respect to a single phase, itwill, of course, be understood by those skilled in the art that it mayjust as well comprise a plurality of phases, in which case, a pluralityof arms 23 would be provided for operating the movable contacts I2 ofthe various phase The arm 23 is shown provided with apin 24 operatingthe member 25 secured to the outer end of movable contact I2. Member 25is arranged to slide on a pair of rods 26, only one of which is shown inthe drawing since the other is obscured from view thereby. It will beapparent that, when the shaft 22 is rotated in a counteris reciprocated.This type of operating mechanism is described in detail in United StatesLetters Patent 2,218,797, granted October 22, 1940,

upon the joint application of Leonard J. Linde and Torild Andersen, andassigned to the same assignee as the present application.

In order to operate the circuit breaker I as well as to supply a blastof fluid through conduit l6 for arc-extinguishing purposes, a source offluid pressure 21 is provided which is preferably air under pressure.This source of air under pressure 21 is connected through a suitableblast valve'28 to conduit l 6 for supplying a blast of air adjacentcontacts II and [2 of circuit breaker IQ for arc-extinguishing purposes.Blast valve 28 is normally biased to the closed position by means ofspring 29 and is operated by means of solenoid 35 which may be energizedat the desired time by any suitable control circuit. The source of fluid21 is also connected with the respective ends of cylinder 18 foroperating circuit breaker It through a four-way control valve 3!. Thisvalve is arranged to control the closing of circuit breaker ID byconnecting source 21 with the righthand end of cylinder 1 8 throughconduit 32; For opening the circuit breaker, on the other hand, valve 31is adapted to interconnect the source of fluid under pressure 12'! withthe left-hand end of cylinder l8 through conduit '33. Valve 31 is soconstructed as to vent one end of cylinder 18 to atmosphere throughconduit 34 whenever the other end of cylinder 18 is subjected topressure from source 27. A suitable spring means 35 is provided to biasvalve 31 to the closed position shown in the diagram. Valve 31 isarranged to be operated for opening circuit breaker M3 by means of anopening solenoid 36 which may be energized from any suitablecontrolcircuit. Similarly, valve '31 is arranged to be operated to control theclosing of circuit breaker 1:0 by means of a closing solenoid '3! whichmay also be energized from any suitable. control circuit. Openingsolenoid 36 and closing .solenoid 31 are preferably controlled in themanner disclosed in United States Letters Patent 2,255,496, grantedSeptember 9, 1941, upon an application of Bryce W. Wyman, and assignedto the same assignee as the present application.

In order to prevent operation of circuit breaker I 0 which might resultin considerable damage thereto as well as to associated apparatus in theevent that the pressure in source 2] fell below a predetermined amount,I provide a mechanical locking means generally indicated at 38 in Figs.1 and 2 which is connected to the source of pressure 21 by means of aconduit 39. This mechanical locking means 38 may be applied to anymovable part of the circuit breaker operating mechanism as will beunderstood by those skilled in the art. However, I have chosen to applyit to operating rod 20 which, as illustrated in Fig. 1. includes aportion of rectangular cross section 29'. Portion 20' of rod 20 isprovided with two pairs of side notches and 4 l the pair of notches 40being in registry with the mechanical locking means 38 when the circuitbreaker is in the closed position shown in Fig. 1 and the notches 6|being in registry with the mechanical locking means 38 when the circuitbreaker is moved to its fully open position.

Referring now to Fig. 2 where the mechanical locking means 38 is shownin enlarged perspective view, it is observed that it includes meanscomprising a pair of interference plungers 42 which are reciprocallymounted in a fixed cylinder block 43. In order to operate interferenceplungers 42 together, I provide a crosshead 44 which interconnects oneend of one of the plungers 32 with the corresponding end of the otherplunger 42. Fixed cylinder block 43 has cooperating openings withinwhich plungers 32 are mounted and these openings are spaced so thatinterference plungers 42 are adapted to engage with the notches 48 or M,depending upon whether the circuit breaker is in the closed or openposition. The fixed cylinder block 43 is provided with extensions 13including semicircular grooves or notches which are adapted to be inregistry with the notches 49 or H of the portion 253 of rod 20 when thecircuit breaker I0 is in either its fully closed or fully open position.When the interference plungers #32 are moved into the notches as or Mand the corresponding semicircular notches in fixed cylinder block 43,rod 29 is mechanically locked in either of its extreme positions andcircuit breaker It} can not be operated.

In order to make crosshead 43 and interference plungers 42 responsive tothe pressure of source 2?, I provide a fiuid motor in fixed cylinderblock 23 comprising a cylinder 55 connected to source p 27 by conduit 39and a piston 4'! reciprocally mounted in cylinder 45. Piston 31 ispreferably connected to crosshead t l as by operating rod 68. Operatingrod GB extends through crosshead M and includes force-transmittingshoulders 49 and by which 'forces either opposing or aiding the fluidpressure in cylinder &6 may be applied to piston ii. Locking means 38should lock circuit breaker it in either its open or closed position ifthe pressure in source 2! falls below a safe operating value.Accordingly, I provide means including a compression spring 5ioperatively connected through an eyebolt 5-2 .and a clevis-type bellcrank 53 to piston 4'! by means of shoulder 49 on operating rod 43 foropposing the fluid pressure of source 2? acting on piston M. Bell crank53 is movable about fixed pivot 54 and has forked ends 55 which fit intoa groove in operating rod 48 between shoulders t9 and 56 so as to moveoperating rod 48 in either direction or be moved by piston -l actingthrough operating rod -58. Bell crank 53 also has forked ends 5 3 forconnection with eyebolt 52 as at 5?. Eyebolt 52 extends throughcompression spring 5| which is supported by spring-retaining member 58mounted on fixed cylinder block 63. Any suitable means for adjusting thecompression of spring 5! may be provided. As illustrated in Fig. 2, Ihave provided a nut 59 on eyebolt 52 by which the compression of springtl is adjusted to such a value as to move interference plungers 52 intoengagement with notches 49 or BI whenever the pressure in source 21falls below a predetermined minimum value below which safe operation ofcircuit breaker It may not be obtained with any degree of assurance.Bell crank 53 is constructed so that the forked ends 55 are adapted toengage with the corner 43" or fixed cylinder block 53, which acts as .astop means to prevent pressures in excess of the minimum pressure insource 21 which is satisfactory for operating circuit breaker I ifrommoving the interference plungers d2 beyond the limiting positionshown in Fig. 2 in which the plungers are just clear of the portion 20'of reciprocating rod 2@. With the above described arrangement, lockingmeans 33 is adapted to lock circuit breaker If) in either the open orclosed position whenever the pressure in source 2! falls below apredetermined value considered safe for operating circuit breaker It,which pressure is determined by the setting of .compression spring 5| asmaybe accomplished by adjusting nut 59.

Under certain conditions, it might be desirable to be able mechanicallyto lock circuit breaker ID in either its open or closed position; forexample when repair work is done thereon or under certain testconditions. Accordingly, I provide means for accomplishing this purposeby utilizing locking means 38 which must be capable of mechanicallylocking circuit breaker l even though the pressure in source 2'! issufliciently high to maintain interference plungers 42 out of engagementwith notches 40 or 4| of the portion 20 of operating rod 20. To permitmechanically locking circuit breaker ID in one of its extreme positions,I provide a hand lever 60 pivotally mounted on pivot 54. Preferably thehand lever is provided with a curved end which, when lever 60 is rotatedabout pivot 54, engages at 60 with the portion 53' of bell crank 53 torotate bell crank 53 in a clockwise direction about pivot 54 as viewedin Fig. 2 and move interference Iplungers 42 against the force of thefluid pressure in cylinder 46 acting on piston 41 into their lockingposition. Hand lever 60 may be mechanically held in this downwardposition holding interference plungers 42 in their locking position bymeans of an extension lug 6| supported from fixed cylinder block 43 andadapted to extend through a saw-cut notch 62 in hand lever 60. Asuitable padlock or pin may be placed through openings 63 and 64 inextension lug BI and hand lever 60 respectively to hold hand lever 60 inthis downward position and consequently maintain interference plungers42 in their locking position even though the fluid pressure in source 21is sufiiciently high for safe circuit breaker operation.

In order to operate circuit breaker 16 manually under no-loadconditions, for example when the pressure in source 21 is below thevalue to maintain interference plungers 42 out of their lockingposition, I provide openings or apertures 65 in bell crank 53 so that,by moving hand lever 60 downwardly and inserting a pin through apertures55, hand lever 60 may then be moved upwardly to cause bell crank 53 torotate in a counterclockwise direction about fixed pivot 54 as viewed inFig. 2, whereupon the forked ends 55 of bell crank 53 engage with theshoulder 50 of operating rod 48 to withdraw interference plungers 42from their locking position against the force of spring means Theoperation of the circuit breaker and mechanical locking meansillustrated in Figs. 1 and 2 will be obvious to those skilled in the artin view of the detailed description included above. If, for any reason,the pressure of source 2! falls below a predetermined value so that itis impossible or undesirable to open circuit breaker Ill safely in theevent of an abnormal current condition, spring means 5| is adapted toovercome the force acting on piston 41 and interference plungers 42 aremoved to engage notches 40 or 4| depending upon the particular positionof circuit breaker l 8 and consequently the circuit breaker is locked ineither its fully open or fully closed position. However, means includinga manual or hand lever 60 are provided whereby locking means 38 may becontrolled so that operation of circuit breaker it! under certainconditions may be obtained even though the pressure has fallen below thePredetermined safe value for such operation or the circuit breaker I 0may be mechanically locked in one of its extreme positions by manualmeans even though the pressure in source 21 is above the predeterminedsafe value.

While I have shown and described a particular embodiment of my inventionas applied to an electric circuit breaker, it will be obvious to thoseskilled in the art that various changes and modiflcations may be madewithout departing from my invention in its broader aspects and I,therefore, in the appended claims aim to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In an electric circuit breaker of the type depending at least in partupon fluid under pressure for operation thereof comprising a pair ofrelatively movable contacts, motive means for producing relativemovement between said contacts, a source of fluid under pressure, amember associated with said motive means and movable thereby, andmechanical locking means responsive to the pressure of said source forlooking said member in a predetermined position and consequentlypreventing operation of said circuit breaker when the pressure of saidsource falls to a value below which safe operation of said circuitbreaker might not be obtained.

2. In an electric circuit breaker of the type depending at least in partupon fluid under pressure for operation thereof comprising a pair ofrelatively movable contacts, motive means for producing relativemovement between said contacts, a source of fluid under pressure, amember associated with said motive means and movable thereby, andmechanical locking means responsive to the pressure of said source forlocking said member in either one of two predetermined positions andconsequently locking said circuit breaker in either the fully open orfully closed position when the pressure of said source falls to a valuebelow which safe operation of said circuit breaker might not beobtained.

3. In an electric circuit breaker of the type depending at least in partupon fluid under pressure for operation thereof comprising a pair ofrelatively movable contacts, motive means for producing relativemovement between said contacts, a source of fluid under pressure amember associated with said motive means and movable thereby, mechanicallocking means responsive to the pressure of said source for locking saidmember in either one of two predetermined positions and consequentlylocking said circuit breaker in either the fully open or fully closedposition when the pressure of said source falls to a value below whichsafe operation of said circuit breaker might not be obtained, and manualmeans for operating asid mechanical locking means to lock said circuitbreaker in either its fully open or fully closed position even thoughthe pressure of said source is above the value below which safeoperation of said circuit breaker might not be obtained.

4. In an electric circuit breaker of the type depending at least in partupon fluid under pressure for operation thereof comprising a pair ofrelatively movable contacts, motive means for producing relativemovement between said contacts, a source of fluid under pressure, amember associated with said motive means and movable thereby, mechanicallocking means responsive to the pressure of said source for locking saidmember in either one of two predetermined positions and consequentlylocking said circuit breaker in either the fully open or fully closedposition when the pressure of said source falls to a value below whichsafe operation of said circuit breaker might not be obtained, and manualmeans for operating said mechanical locking means to permit operation ofsaid circuit breaker under predetermined conditions even though thepressure on said source falls to a value below which safe operation ofsaid circuit breaker might not be obtained.

5. In an electric circuit breaker 'of the type depending at least inpart upon fluid under pressure for operation thereof comprising 'a pairof relatively movable contacts, motive means for producing relativemovement between said contacts, a source of fluid under pressure, amember associated with said motive means and movable thereby including anotch therein, mechanical locking means including an interferenceplunger adapted to engage with said notch for locking said member, andconsequently said circuit breaker in a predetermined position, a fluidmotor associated with said interference plunger responsive to thepressure of said source of fluid and tending to force said plunger outof engagement with said notch, and means operatively connected to saidfluid motor for opposing the action of said fluid under pressure, saidlastmentioned means being so adjusted relative to the action of saidfluid under pressure on said fluid motor to cause said interferenceplunger to engage said notch whenever the pressure of said source fallsto a value below which safe operation of said circuit breaker is notassured.

6. In an electric circuit breaker of the type depending at least in partupon fluid under pressure for operation thereof comprising a pair ofrelatively movable contacts, motive means for producing relativemovement between said contacts, a source of fluid under pressure, amember associated with said motive means and movable thereby having twopairs of spaced side notches therein, mechanical locking means includingmovable plungers for engagingone or the other of said pairs of sidenotches to lock said member and consequently said circuit breaker ineither the fully open or the fully closed position, a fluid motoroperatively connected to said plungers and responsive to the pressure ofsaid source for forcing said plungers out of engagement with saidnotches, spring means for opposing said fluid motor to tend to causeengagement of said plungers with said notches, and means for adjustingsaid spring means to cause said plungers to engage either of said pairsof notches whenever the pressure of said source falls below apredetermined safe operating value.

CARL THUMIM.

